The invention relates to improvements in apparatus for discharging flowable materials, and more particularly to improvements in apparatus which are designed to simultaneously discharge two or more fluids. Typical examples of such apparatus are so-called spray guns which can discharge mixtures of gaseous and liquid fluids, and so-called "nozzles" which can be used to admit fuel into the tanks of motor vehicles.
As used herein, the term "fluid" or "flowable material" is intended to denote a gaseous fluid, a liquid and/or a flowable solid material.
It is known to employ a gun of the type having a pistol grip handle and a barrel to admit fuel into the tank of a motor vehicle. It is also known to design a fuel-admitting gun or "nozzle" in such a way that it can simultaneously discharge a plurality of different fuels, e.g., a mixture of gasoline and oil of the type used in two stroke cycle engines. It is further known to employ an electrostatic or other spray gun to discharge a mixture of a gaseous fluid and a liquid or comminuted solid material. Similar apparatus are used for simultaneous discharge of different adhesive substances. Certain presently known guns are convertible so that they can discharge a single flowable medium or a mixture or discrete streams of different flowable media.
A presently known gun which is distributed by the assignee of the present application employs a housing having a barrel and a pistol grip handle. A first conduit is connected to the handle to supply a stream of air which is admitted into and is discharged from the barrel in response to opening of a valve which is controlled by a manually operable trigger. A second conduit serves to supply paint, wax, a flowable synthetic plastic material or another non-gaseous fluid to the front end of the barrel close to the locus where the two fluids are mixed prior to being discharged or where the two fluids are discharged without mixing. A drawback of such apparatus is that the weight of the second conduit and of the non-gaseous fluid therein affects the balance of the apparatus, i.e., the apparatus is top heavy or front heavy and is hard to manipulate when in actual use. In other words, the second conduit and its contents tend to pull the front end of the barrel in a downward direction so that the hand which holds the handle at the rear end of the barrel and controls the trigger must continuously resist the tendency of the barrel and of the second conduit to tilt the barrel in a direction to move the front end of the barrel to a level below the handle.
Another drawback of presently known spray guns and similar apparatus which are used to discharge a plurality of flowable materials is that the discrete conduits which supply different flowable materials tend to become entangled and resist changes in orientation of the barrel. Entanglement of the conduits can result in constriction of the path or paths for flowable material or materials in one or more conduits so that the ratio of fluid media which are discharged by such apparatus is changed to thereby affect the quality of the mixture issuing from the apparatus. The utilization of relatively stiff conduits which are less likely to be deformed contributes to the bulk and weight of conventional apparatus. Moreover, the manipulation of a relatively heavy and bulky apparatus is tiresome to the operator and can affect the quality of the work, e.g., when the apparatus is used to spray or otherwise apply a mixture, or several discrete streams or sprays, of flowable materials.
German Utility Model No. 1 857 492 to British Transport Commission discloses a lance-like cleaning implement which employs a substantially L-shaped housing for two conduits and a nozzle. One of the conduits admits compressed air and the other conduit admits pressurized water or another liquid. The liquid is atomized on admission into the nozzle so that the stream of air which issues from the nozzle contains a mist of finely atomized liquid. The implement of this Utility Model is intended for use as a means for cleaning buses or railroad cars and for analogous purposes.
German Auslegeschrift No. 1 059 809 of Redder discloses a spray gun wherein a first conduit admits compressed air into the lower end of the handle and two additional conduits serve to admit lacquer and a hardening agent into the front end of the barrel. The front end of the barrel has several orifices which discharge air and sprays of lacquer and hardening agent. The spray gun of Redder is top heavy and is difficult to manipulate, especially for relatively long periods of time.
German Utility Model No. 76 33 342.1 to Gerlieva Spruh- und Antriebstechnik discloses a spray gun which is similar to that of Redder except that the front portion of the barrel supports a single liquid-admitting conduit. The liquid is drawn by one or more streams of compressed air which are admitted into the rear end of the barrel and flow toward and into the front end. This gun exhibits all drawbacks of the apparatus of Redder.